Disk-like recording medium, disk recording apparatus and disk recording method, and disk playback apparatus and disk playback method

ABSTRACT

Disclosed is a disk-like recording medium, a disk recording apparatus and a disk recording method, and a disk playback apparatus and a disk playback method. Disk ID is recorded over a circle of a burst cutting area on an optical disk. The circle is divided into n blocks, each of the blocks is divided into m frames, and ID information is recorded in each of the frames with k channel bits.

BACKGROUND OF THE INVENTION

The present invention relates to a disk-like recording medium, a diskrecording apparatus and a disk recording method, and a disk playbackapparatus and a disk playback method, and particularly to a disk-likerecording medium, a disk recording apparatus and a disk recordingmethod, and a disk playback apparatus and a disk playback method thatmake it possible to reproduce auxiliary information of a disk reliably.

As write-once or rewritable disks are spread, data replication of whichis prohibited (for example contents data such as music data and videodata protected by copyright or the like) may be illegally copied. On aDVD (Digital Versatile Disk), for example, a BCA (Burst Cutting Area) isprovided to prevent illegal copying between disks.

The BCA provided on a DVD will be described with reference to FIG. 1. ABCA 2 of a DVD 1 (DVD-ROM (Read Only Memory) or DVD-RAM (Random AccessMemory)) is irradiated with pulse laser light of a YAG(yttrium-aluminum-garnet) laser at a factory prior to shipment, wherebystripes (bar code) is formed along the innermost circumference byremoving, in a radial direction, narrow stripes of reflecting film madeof aluminum or the like formed on an inner side of the disk. The stripesshow auxiliary information such for example as an ID number and otheridentification information and an encryption key. The BCA 2 is formedfor about 330° along the innermost circumference of the DVD 1.

Data structure of data recorded in the BCA 2 is shown in FIG. 2.

The data recorded in the BCA 2 has a row of five bytes as one unit. Afirst one byte of the row of five bytes is a sync byte (SB) or a resync(RS). A BCA-Preamble is recorded in four bytes of a first row. TheBCA-Preamble is data including only 0s. Four bytes of each row in a BCAdata field is an information area or an EDC (error detection code). Fourbytes of each row in an ECC (error correction code) area is errorcorrection code. A BCA-Postamble is recorded in a last row.

When the data recorded in the BCA 2 is to be reproduced, a reproducingapparatus generates a clock on the basis of a reproduced signal of theBCA-Preamble part by means of a PLL (Phase Locked Loop), and performsdemodulation and error correction by a predetermined method on the basisof the clock to thereby reproduce the data.

However, if the PLL loses synchronism in reproducing the data recordedin the BCA due to some defect, for example, the data cannot bereproduced until the PLL regains synchronism. This means that reproduceddata is lost for a period when the synchronism of the PLL is lost.

Also, if a synchronization signal (sync) is lost once due to a defect orthe like, data may be lost until a next synchronization signal isdetected.

If the amount of lost data is larger than an error correction capability(that is, if there is a local major defect), data cannot be reproduced.The information recorded in the BCA 2 is ID information unique to eachdisk and the like. It may be related to the entire data on the disk (forexample determine whether contents recorded on the DVD 1 may bereproduced or not). Therefore, high reliability is required for datarecording and reproduction recorded in the BCA2. In order to reduce theamount of lost data, a method of frequently inserting a synchronizationsignal for resynchronization is conceivable; however, such insertion ofthe redundant synchronization signal reduces the amount of datarecordable in the BCA.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above, and it isaccordingly an object of the present invention to enable reliablereproduction of data in the BCA.

To achieve the above object, according to a first aspect of the presentinvention, there is provided a disk-like recording medium including: nblocks arranged in a circle of a second area and each having a lengthobtained by dividing the second area into n equal parts in acircumferential direction; and m frames arranged in one of the blocksand each having a length obtained by dividing the block into m equalparts in the circumferential direction; wherein auxiliary information isarranged in the frames in such a manner as to be at equal intervals inthe circumferential direction, and a synchronization signal is disposedin each of the frames.

In one of the frames, k channel bits may be arranged at intervalsobtained by dividing the frame into k equal parts.

The auxiliary information may be modulated by a modulation methodcapable of word synchronization or bit synchronization.

The modulation method may be a phase encoding method or a 4-1 modulationmethod.

When a value of the m is two or more, the number of kinds ofsynchronization signals may be two or more and m or less.

An error correction code can be added to the auxiliary information.

Identical data can be disposed in each of the n blocks.

According to a second aspect of the present invention, there is provideda disk recording apparatus including: rotating means for rotating adisk; generating means for generating a channel clock corresponding toan interval obtained by dividing one frame into k equal parts where nblocks each having a length obtained by dividing a second area into nequal parts in a circumferential direction are generated and m frameseach having a length obtained by dividing one of the blocks into m equalparts in the circumferential direction are generated, the channel clockbeing required for recording auxiliary information; control means forcontrolling rotation of the disk so that one rotation of the disk is insynchronism with a cycle of n×m×k channel clocks; modulating means formodulating the auxiliary information on the basis of the channel clockgenerated by the generating means; and recording means for recording theauxiliary information modulated by the modulating means on the disk.

According to a third aspect of the present invention, there is provideda disk recording method including: a rotating step for rotating a disk;a generating step for generating a channel clock corresponding to aninterval obtained by dividing one frame into k equal parts where nblocks each having a length obtained by dividing a second area into nequal parts in a circumferential direction are generated and m frameseach having a length obtained by dividing one of the blocks into m equalparts in the circumferential direction are generated, the channel clockbeing required for recording auxiliary information; a control step forcontrolling rotation of the disk so that one rotation of the disk is insynchronism with a cycle of n×m×k channel clocks; a modulating step formodulating the auxiliary information on the basis of the channel clockgenerated by processing of the generating step; and a recording step forrecording the auxiliary information modulated by processing of themodulating step on the disk.

According to a fourth aspect of the present invention, there is provideda disk playback apparatus including: rotating means for rotating a diskat a constant angular velocity; playback means for playing back thedisk; generating means for generating a clock having a frequency twicen×m×k or higher; and demodulating means for sampling a signal outputtedby the playback means on the basis of the clock generated by thegenerating means and demodulating channel bits, or words whilecorrecting the channel bits, or the words.

The disk playback apparatus can further include correcting means formaking error correction on the basis of an error correction codeincluded in the auxiliary information and determining correct auxiliaryinformation by majority rule.

The correcting means can make error correction on auxiliary informationobtained by collecting portions determined by majority rule.

According to a fifth aspect of the present invention, there is provideda disk playback method including: a rotating step for rotating a disk ata constant angular velocity; a playback step for playing back the disk;a generating step for generating a clock having a frequency twice n×m×kor higher; and a demodulating step for sampling a signal outputted byprocessing of the playback step on the basis of the clock generated byprocessing of the generating step and demodulating channel bits, orwords while correcting the channel bits, or the words.

The disk-like recording medium according to the present inventionincludes: n blocks arranged by dividing a circle of a second area into nequal parts; and m frames arranged in each of the blocks; whereinauxiliary information is arranged in the frames in such a manner as tobe at equal intervals in a circumferential direction, and asynchronization signal is disposed in each of the frames.

The disk recording apparatus and disk recording method according to thepresent invention control rotation of a disk so that one rotation of thedisk is in synchronism with a cycle of n×m×k channel clocks, modulateauxiliary information on the basis of the channel clocks, and thenrecord the auxiliary information on the disk.

The disk playback apparatus and the disk playback method according tothe present invention sample a reproduced output signal from a disk by aclock having a frequency twice n×m×k or higher, and demodulate channelbits, or words while correcting the channel bits, or the words.

The above and other objects, features and advantages of the presentinvention and the manner of realizing them will become more apparent,and the invention itself will best be understood from a study of thefollowing description and appended claims with reference to the attacheddrawings showing some preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of assistance in explaining a burst cutting area ona related-art DVD;

FIG. 2 shows a recording format of the burst cutting area in FIG. 1;

FIG. 3 shows structure of an optical disk to which the present inventionis applied;

FIG. 4 shows a recording format of the burst cutting area in FIG. 3;

FIG. 5 is a diagram of assistance in explaining an ECC format in theburst cutting area in FIG. 3;

FIG. 6 is a diagram of assistance in explaining PE modulation;

FIGS. 7A and 7B are diagrams of assistance in explaining sync patternsof frame sync in FIG. 4;

FIG. 8 is a block diagram showing a configuration of a disk ID recordingapparatus for recording disk ID information on the optical disk of FIG.3;

FIG. 9 is a block diagram showing a configuration of a disk recordingand playback apparatus for recording or reproducing data on the opticaldisk having disk ID recorded by the disk ID recording apparatus of FIG.8;

FIGS. 10A through 10E are diagrams of assistance in explaining operationof a demodulation unit in FIG. 9;

FIG. 11 is a diagram of assistance in explaining operation of thedemodulation unit in FIG. 9;

FIG. 12 shows another format in the burst cutting area of the opticaldisk of FIG. 3;

FIG. 13 is a diagram of assistance in explaining 4-1 modulation;

FIGS. 14A and 14B are diagrams of assistance in explaining sync patternsof frame sync in FIG. 12;

FIG. 15 is a block diagram showing a configuration of a disk IDrecording apparatus for recording disk ID in the format of FIG. 12;

FIGS. 16A through 16G are diagrams of assistance in explaining operationof playing back an optical disk recorded in the format of FIG. 12;

FIG. 17 is a diagram of assistance in explaining the operation ofplaying back the optical disk recorded in the format of FIG. 12;

FIG. 18 is a diagram showing another ECC format;

FIGS. 19A and 19B are diagrams showing other sync patterns of framesync; and

FIG. 20 is a diagram showing another disk ID recording format.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will hereinafter bedescribed with reference to the drawings.

In the present invention, as shown in FIG. 3, ID information unique toan optical disk 26 is recorded in a burst cutting area (BCA) 26A on theoutside (in this case, on the innermost side) of a data area 26B withinan inner radius of the optical disk 26 in which area contents data isrecorded. As shown in FIG. 3, the burst cutting area 26A is created insuch a manner as to form a continuous circle.

FIG. 4 shows an example of a disk ID recording format recorded in theBCA 26A. As shown in FIG. 4, the circle is divided into n equal parts(in this case, n=6), thereby forming n blocks.

Each of the blocks is further divided into m frames (in the example ofFIG. 4, m=2). Each of the frames is divided into k parts (in this case,k=234). The ID information is recorded with k channel bits.

Ten channel bits at the front of each of the frames is frame sync. Thesucceeding 224 channel bits forms a data area.

Here, it is assumed that disk ID information is modulated by a PE (PhaseEncode) modulation method, for example. The PE modulation convertsone-bit data into two channel bits, and therefore 112 data bits (224channel bits) can be recorded in a single frame, while 224 informationbits (28 bytes) can be recorded in a single block.

In this example, disk ID information in an ECC format as shown in FIG. 5is recorded in each of the blocks. In this example, 12-byte parity isadded to 16-byte data, and the disk ID information is encoded by aReed-Solomon code RS (32, 16, 13) of a Galois field GF (2⁸). Threeblocks each have the same ECC format. Thus, 14 bytes of 16-byte IDinformation ID_(m) is disposed as information bits of 14 bytes in afirst frame of each of the blocks. The remaining two bytes of the IDinformation ID_(m) and 12-byte parity are disposed as information bitsof 14 bytes in the next frame.

This means triple writing of the same disk ID information in the circleof the disk. This triple writing is in effect equivalent to forming aproduct code of distance 3 in a vertical direction.

As shown in FIG. 6, the PE modulation is a code indicating a data bit bythe position of a mark (1) (bit indicated in black in FIG. 6) and aspace (0) (bit indicated in white in FIG. 6). In the example of FIG. 6,a data bit of “0” is converted into channel bits (word) of “10” and adata bit of “1” is converted into channel bits (word) of “01”. In the PEmodulation, the channel bits are inverted at a center of two channelbits (center of a word) indicating a data bit. Thus, in the case of databits, marks or spaces do not occur continuously for three channel bitsor more.

Accordingly, a sync pattern indicating sync bits (frame sync) can beformed by arranging marks or spaces continuously in three channel bitsor more. FIGS. 7A and 7B each show a sync pattern of frame sync.

As shown in FIGS. 7A and 7B, two kinds of sync patterns of six channelbits are provided as frame sync patterns in which marks and spaces eachoccur continuously in three channel bits. When channel bits of dataimmediately preceding a frame sync are “01”, “000111” is used as theframe sync, and “01” is added as a succeeding sync pattern. On the otherhand, when channel bits of data immediately preceding a frame sync are“10”, “111000” is used as the frame sync, and “10” is added as asucceeding sync pattern. Channel bits of “01” or “10” are further addedas sync ID after the above sync body (“00011101” or “11100010”). Thus, atotal of 10 channel bits form a frame sync. Hereinafter, a frame syncwhen a sync ID pattern is “0” (channel bits=“10”) (FIG. 7A) will bereferred to as SA, and a frame sync when a sync ID pattern is “1”(channel bits=“01”) (FIG. 7B) will be referred to as SB.

A frame sync SA is used to indicate that its frame is a first frame of ablock, whereas a frame sync SB is used to indicate that its frame isother than a first frame of each of the blocks. Hence, the number offrames having frame syncs SA is equal to the number of blocks.

FIG. 8 is a block diagram showing a configuration of a disk ID recordingapparatus 11 to which the present invention is applied.

A register 21 stores the disk ID information that has been subjected toerror correction coding in accordance with the ECC format shown in FIG.5. A PE modulation unit 22 reads the disk ID information stored in theregister 21, subjects the disk ID information to PE modulation, and thenoutputs the result to a laser 23. The PE modulation unit 22 subjects thedisk ID information read from the register 21 to the PE modulationaccording to a clock (channel clock) inputted from a VCO (voltagecontrolled oscillator) 33 and then inserts sync patterns to therebygenerate data to be recorded in the BCA 26A of the optical disk 26. ThePE modulation unit 22 outputs the data to the laser 23.

The laser 23 is a YAG laser, for example, and irradiates the opticaldisk 26 with a high-power laser beam via a mirror 24 and an object lens25. The object lens 25 includes a cylindrical lens, for example, andirradiates the BCA 26A of the optical disk 26 with the laser beamentering the object lens 25. Thus, a reflecting film of the optical disk26 is changed irreversibly, whereby the disk ID information is recordedas a bar code. That is, even if the optical disk is a rewritablerecording medium, the auxiliary data such as disk ID recorded in the BCA26A is recorded on the optical disk 26 as unrewritable data.

A spindle motor 27 rotates the optical disk 26 under control of aspindle servo control unit 28, and an FG (Frequency Generator) signalgenerator not shown in the figure provided within the spindle motor 27generates an FG signal that forms one pulse each time the optical disk26 (spindle motor 27) rotates by a predetermined angle, and then outputsthe FG signal to the spindle servo control unit 28. Under control of acontroller 29, the spindle servo control unit 28 controls the spindlemotor 27 on the basis of the FG signal inputted from the spindle motor27 so that the spindle motor 27 rotates at a predetermined rotationalspeed. Also, the spindle servo control unit 28 outputs the FG signalinputted from the spindle motor 27 to the controller 29 and a PC (PhaseComparator) 31.

The controller 29 controls the spindle servo control unit 28 accordingto an operating signal inputted from an operating unit not shown in thefigure to thereby drive the spindle motor 27 and thus rotate the opticaldisk 26. In addition, the controller 29 generates a control signal forcontrolling a frequency dividing ratio of a frequency divider 30 on thebasis of the FG signal inputted from the spindle servo control unit 28,and then outputs the control signal to the frequency divider 30.

The frequency divider 30, the PC 31, an LPF (Low Pass Filter) 32, andthe VCO 33 form a PLL.

The frequency divider 30 divides the clock outputted by the VCO 33 intoa value 1/N (frequency dividing ratio) set on the basis of the controlsignal inputted from the controller 29, and then outputs the result tothe PC 31. The PC 31 compares the phase of a clock inputted from thefrequency divider 30 with the phase of the FG signal inputted from thespindle servo control unit 28 to thereby generate a phase differencesignal, and then outputs the phase difference signal to the LPF 32. TheLPF 32 removes a high-frequency component from the signal inputtedthereto, and then outputs the result to the VCO 33. The VCO 33 changesthe phase (frequency) of the clock that the VCO 33 outputs byoscillation on the basis of a voltage applied to a control terminal ofthe VCO 33 (that is, the output from the LPF 32).

The clock outputted by the VCO 33 is inputted to the PE modulation unit22 and also to the frequency divider 30. The VCO 33 is controlled sothat a phase difference between the output of the frequency divider 30and the FG signal outputted by the spindle servo control unit 28 becomesconstant. Therefore, the output of the VCO 33 is a signal oscillating insync with the FG signal at a frequency N times that of the FG signal.The PE modulation unit 22 outputs the data in the format described withreference to FIG. 4 according to the clock inputted from the VCO 33 tothe laser 23.

A drive 34 is connected to the controller 29. A magnetic disk 41, anoptical disk 42, a magneto-optical disk 43, or a semiconductor memory 44is inserted into the drive 34 as required. A necessary computer program,for example, is read from the magnetic disk 41, the optical disk 42, themagneto-optical disk 43, or the semiconductor memory 44, and is suppliedto the controller 29.

Operation of the disk ID recording apparatus 11 will next be described.When a command to start recording is issued, the controller 29 controlsthe spindle servo control unit 28 to rotate the spindle motor 27 at apredetermined speed. The spindle motor 27 generates an FG signalcorresponding to its rotation, and then supplies the FG signal to thespindle servo control unit 28. The spindle servo control unit 28supplies the FG signal to the PC 31.

The PC 31 compares the phases of two input signals with each other, andthen supplies a signal of a phase error between the two signals to theVCO 33 via the LPF 32. The VCO 33 generates a clock having a phase and afrequency corresponding to a signal (control voltage) supplied from theLPF 32.

The clock outputted by the VCO 33 is supplied to the frequency divider30 to be divided by a predetermined frequency dividing ratio set via thecontroller 29, and then supplied to the PC 31.

Thus, the clock (channel clock) outputted by the VCO 33 has a cycle of1/(n×m×k) of one rotation of the optical disk 26 (spindle motor 27). Forexample, when an FG wave number per rotation of the FG signal is 36 andthe value of the frequency dividing ratio 1/N of the frequency divider30 is 1/39, the VCO 33 generates a channel clock having a cycle of1/(3×2×234) of the time period of one rotation of the spindle motor 27(optical disk 26).

The PE modulation unit 22 subjects disk ID information supplied from theregister 21 to PE modulation based on the channel clock supplied fromthe VCO 33 and then outputs the disk ID information to the laser 23. Thelaser 23 generates a laser beam on the basis of the data supplied fromthe PE modulation unit 22 to thereby irradiate the optical disk 26 withthe laser beam via the mirror 24 and the object lens 25. Thus, the diskID information is recorded concentrically over a plurality of tracks inthe BCA 26A of the optical disk 26 at a factory prior to shipment.

Incidentally, depending on output intensity required by the laser 23,the cycle of the channel clock outputted by the VCO 33 may be multipliedby r to be r/(n×m×k). In this case, a frequency dividing coefficient Nof the frequency divider 30 is also multiplied by r.

FIG. 9 is a block diagram showing a configuration of a disk recordingand playback apparatus 51 for recording data and reproducing datarecorded in the data area 26B of the optical disk 26 having the disk IDinformation recorded in a manner as described above in its BCA 26A.

A CPU 61 controls parts of the disk recording and playback apparatus 51according to an operating signal inputted from an operating unit notshown in the figure to thereby record data and reproduce data recordedin the data area 26B of the optical disk 26. In reproducing data orrecording data, the CPU 61 outputs the disk ID information of theoptical disk 26 retained by a register 71 to a decryption processingunit 74 or an encryption processing unit 75. Also, the CPU 61 generatesa control signal to rotate or stop the optical disk 26, and outputs thecontrol signal to a servo control unit 63.

The servo control unit 63 makes an optical pickup 64 seek to a specifiedposition on the optical disk 26 on the basis of the control signalinputted from the CPU 61, and also effects tracking control and focuscontrol of the optical pickup 64 on the basis of a tracking error signal(TK) and a focus error signal (FS) supplied from a matrix amplifier (MA)65. A spindle motor 62 rotates the optical disk 26 at a predeterminedrotational speed under control of the servo control unit 63.

In reproducing the disk ID information, the optical disk 26 is rotatedby a CAV (Constant Angular Velocity) method.

The optical pickup 64 is held by a specified sled mechanism so as to beable to move in a radial direction of the optical disk 26. When datarecorded on the optical disk 26 is to be read, the optical pickup 64irradiates the optical disk 26 with a laser beam according to a controlsignal inputted from the servo control unit 63, receives the reflectedbeam, converts the reflected beam into an electric signal, and thenoutputs the electric signal to the matrix amplifier 65. When the opticalpickup 64 records new data on the optical disk 26, the optical pickup 64irradiates the optical disk 26 with a laser beam on the basis of dataoutputted from a modulation unit 77 to thereby record the new data inthe data area 26B of the optical disk 26.

The matrix amplifier 65 processes the signal inputted from the opticalpickup 64, and then outputs a reproduced signal of data corresponding tothe disk ID information recorded in the BCA 26A of the optical disk 26to an LPF 66. Also, the matrix amplifier 65 generates a tracking errorsignal whose signal level changes according to an amount of trackingerror and a tracking error signal whose signal level changes accordingto an amount of focus error, and then outputs the signals to the servocontrol unit 63. In addition, the matrix amplifier 65 outputs areproduced signal of data recorded in the data area 26B of the opticaldisk 26 to a demodulation unit 72.

The LPF 66 removes a high-frequency component of the signal inputtedthereto to thereby suppress variation in the reproduced signal caused bynoise, and then outputs the result to a comparator 67. The comparator 67binarizes the signal inputted thereto by comparing the signal with apredetermined level. A demodulation unit 68 samples the signal inputtedthereto on the basis of a sampling clock inputted from a quartzoscillator 69, makes channel position correction, performs demodulation(in this case, PE demodulation), and then outputs the result to an ECC(Error Check and Correct) unit 70. A sampling clock number per rotationof the disk is set to be n×m×k×p (n, m, and k are numerical values basedon the disk ID recording format described with reference to FIG. 4, andp is an integer of two or more). The ECC unit 70 supplies thedemodulated data (disk ID information) inputted thereto to the register71 for storage.

In the meantime, the demodulation unit 72 demodulates data (contentsdata) supplied from the matrix amplifier 65, and then supplies thedemodulated data to an ECC unit 73. The ECC unit 73 subjects thedemodulated data inputted thereto to error correction processing, andthen supplies the result to the decryption processing unit 74. Thedecryption processing unit 74 decrypts the contents data supplied fromthe ECC unit 73 on the basis of the disk ID information supplied fromthe register 71, and then outputs the result to an apparatus not shownin the figure.

The encryption processing unit 75 encrypts contents data inputtedthereto on the basis of the disk ID information supplied from theregister 71, and then outputs the result to an ECC unit 76. The ECC unit76 adds an error correction code to the encrypted contents data inputtedthereto, and then outputs the result to the modulation unit 77.

A magnetic disk 91, an optical disk 92, a magneto-optical disk 93, or asemiconductor memory 94 is inserted into a drive 81 as required. Thedrive 81 supplies a program read from the magnetic disk 91, the opticaldisk 92, the magneto-optical disk 93, or the semiconductor memory 94 tothe CPU 61.

Operation of the disk recording and playback apparatus 51 will next bedescribed. When the optical disk 26 is inserted into the disk recordingand playback apparatus 51, the CPU 61 controls the servo control unit 63to rotate the spindle motor 62 at a constant angular velocity (by theCAV method). This velocity is the same as the velocity at which thespindle motor 27 of the disk ID recording apparatus 11 of FIG. 8 rotatesthe optical disk 26.

At this point in time, the servo control unit 63 moves the opticalpickup 64 in a radial direction of the optical disk 26 to play back theBCA 26A of the optical disk 26.

Reproduced data outputted from the optical pickup 64 is inputted fromthe matrix amplifier 65 to the comparator 67 via the LPF 66 to bebinarized. The demodulation unit 68 samples the binarized data inputtedfrom the comparator 67 on the basis of a sampling clock supplied fromthe quartz oscillator 69, and thereby demodulates the data. Also, thedemodulation unit 68 performs processing for correcting channel bits andwords. The processing will be described later in detail.

The demodulated data outputted from the demodulation unit 68 is suppliedto the ECC unit 70 to be subjected to error correction processing basedon an error correction code. The result is supplied to the register 71to be stored therein. Thus, the disk ID information recorded in the BCA26A of the optical disk 26 is stored in the register 71.

When a command to record contents data is issued, the CPU 61 controlsthe servo control unit 63 to rotate the optical disk 26 by a CLV methodvia the spindle motor 62.

The encryption processing unit 75 encrypts contents data inputted froman apparatus not shown in the figure on the basis of the disk IDinformation stored in the register 71, and then outputs the contentsdata to the ECC unit 76. The ECC unit 76 adds an error correction codeto the contents data inputted from the encryption processing unit 75,and then outputs the resulting contents data to the modulation unit 77.The modulation unit 77 modulates the contents data inputted from the ECCunit 76 by the PE method or another predetermined modulation method, andthen outputs the resulting contents data to the optical pickup 64. Theoptical pickup 64 records the contents data inputted from the modulationunit 77 in the data area 26B of the optical disk 26.

When a command to reproduce the contents data thus recorded is issued,the CPU 61 controls the servo control unit 63 to rotate the optical disk26 by the CLV method as in the case as described above. The opticalpickup 64 plays back the data-area 26B of the optical disk 26, and thenoutputs the reproduced data to the matrix amplifier 65. The matrixamplifier 65 supplies the reproduced data to the demodulation unit 72.The demodulation unit 72 demodulates the reproduced contents datainputted thereto by a demodulation method corresponding to themodulation method of the modulation unit 77, and then outputs theresulting data to the ECC unit 73. The ECC unit 73 subjects thedemodulated data inputted from the demodulation unit 72 to errorcorrection processing, and then supplies the resulting data to thedecryption processing unit 74. The decryption processing unit 74decrypts the contents data (encrypted contents data) inputted from theECC unit 73 on the basis of the disk ID information inputted from theregister 71, and then outputs the result to an apparatus not shown inthe figure.

As described above, encrypted contents data is recorded in the data area26B of the optical disk 26. Therefore, even if the encrypted contentsdata is copied onto other disks as it is by a computer or the like, itis not possible to copy the disk ID information, thereby preventingdecryption of the contents data. Thus, it is possible to practicallycontrol illegal copying of contents data in large quantities.

The channel position correction made by the demodulation unit 68 willnext be described with reference to FIGS. 10A through 10E. In this case,description will be made assuming that p=3.

A reproduced pit waveform (FIG. 10A) outputted from the LPF 66 isbinarized by the comparator 67, and then inputted to the demodulationunit 68 as a binarized pit signal (FIG. 10B). The demodulation unit 68includes counters 1 to 3 (not shown). The counter 1 (FIG. 10C) countsthe number of clocks (0 to p−1) within a channel bit. The counter 2(FIG. 10D) counts the number of two channel bits of the PE modulation.The counter 3 (FIG. 10E) counts the number of bits (words) of the PEmodulation.

The channel position correction is made by utilizing the fact that inthe PE modulation, bits are invariably inverted at a center of a pit(that is, center of a word “10” or “01” shown in FIG. 6). Specifically,in timing A in FIGS. 10B through 10E, even though the value of thecounter 3 is not changed (even though at a center of a pit), level ofthe binarized pit signal is inverted, and therefore the value of thecounter 1 immediately after the timing A is corrected to be “0”. Also,the channel position correction is made by utilizing the fact that whenthe same data bits occur continuously, channel bits are inverted at apoint between the data bits (between the words). Specifically, in timingB in FIGS. 10B through 10E, when the value of the counter 3 is changed(at a point between words), the level of the binarized pit signal isinverted, and thus the values of the counters 1 and 2 are corrected tobe “0”.

A plurality of frame syncs are arranged at equal intervals for onerotation of the optical disk 26. Therefore, frame syncs are endlesslygenerated in a constant cycle as the optical disk 26 is rotated. Hence,even when a frame sync of a frame is not detected, it is possible toreproduce data succeeding the frame sync without loss of the data on thebasis of interpolating timing of a frame sync previously detected.

As shown in FIG. 11, when a frame sync (“00011101XX” or “11100010XX”)(FIGS. 7A and 7B) is detected, the values of the counters 1 to 3 are allinitialized to “0”.

The ECC unit 70 is supplied with the demodulated data (that is, the diskID information including parity written triply as described withreference to FIG. 4), and then subjects the data to error correctionprocessing. Each piece of the triply written disk ID information issubjected to error correction. When a result of error correction of athird block is different from results of error correction of the othertwo blocks (a first and a second block), for example, the results oferror correction of the first block and the second block are used as thedisk ID information under a majority rule. The ECC unit 70 outputs theerror-corrected disk ID information to the register 71 for storage.

The ECC unit 70 can also determine correct words in each of the blocksby majority and then perform error correction processing on a codegenerated by collecting correct words.

For example, when a first word in the first block coincides with a firstword in the second block and a first word in the third block isdifferent from the first words in the first block and the second block,the first word in the first block (or the second block) is used as acorrect word. When a second word in the second block coincides with asecond word in the third block and a second word in the first block isdifferent from the second words in the second block and the third block,the second word in the second block (or the third block) is used as acorrect word. Other correct words are collected in a similar manner onthe basis of the majority rule to reconstruct a single piece of disk IDinformation. Then the disk ID information is subjected to errorcorrection processing.

It is assumed that disk ID is reproduced without using a tracking servo,as described above. Therefore, when the reproducing operation isrepeatedly performed over a plurality of rotations of the optical disk26, a different reproduction result (reproduced data) may be obtainedbecause of a slightly shifted radial tracking position or the like.Accordingly, the reproducing operation or correcting operation can beperformed over a plurality of rotations of the optical disk 26.

As a second embodiment, modulation of disk ID information using a 4-1modulation for recording will next be described.

FIG. 12 shows a disk ID recording format in this case.

Also in this case, as in the first embodiment, the circle of the BCA 26Aof the optical disk 26 is divided into three equal parts, therebyforming three blocks. Each of the blocks is formed by two frames eachhaving a sync block SA or SB at the front. Each of the frames has aframe sync of 14 channel bits, and its information bits are 112 databits. The 4-1 modulation converts data of 112 bits into 392 channelbits, and therefore the number of channel bits of a single frame is 406(hence, n=3, m=2, and k=406). Disk ID information of 224 bits, that is,28 bytes can be recorded in a single block.

As shown in FIG. 13, the 4-1 modulation is a modulation method thatmodulates two data bits into seven channel bits. First three channelbits form a sync pattern denoted by “010”, and succeeding four channelbits form a data portion, which indicates data by a position of “1”within the four channel bits. When two data bits before the modulationare “00”, the data portion is “1000”; when two data bits before themodulation are “01”, the data portion is “0100”; when two data bitsbefore the modulation are “10”, the data portion is “0010”; when twodata bits before the modulation are “11”, the data portion is “0001”.One word is formed by the combined seven channel bits of the syncpattern and the data portion.

In the PE modulation method used in the first embodiment, equal numbersof logical “0s” and logical “1s” appear. Accordingly, in that case,substantially half of the reflecting film in the BCA 26A is removed. Onthe other hand, in the 4-1 modulation, a ratio of logical “0s” tological “1s” is 5:2. Accordingly, the amount of reflected light islarger than when disk ID information is recorded by the PE modulation.Thus, the 4-1 modulation has an advantage of making it easier to effectservo control such as focus control during the reading of data, forexample.

Also in this example, the ECC format of the disk ID information is thesame as described with reference to FIG. 5. The disk ID information isencoded by an RS (32, 16, 13) code of GF (2⁸), and 12-byte parity isadded to form one block. The same block is written triply around thedisk.

FIGS. 14A and 14B each show a sync pattern of a frame sync in the secondembodiment.

In the 4-1 modulation, the position of a logical “1” is fixed in a syncpattern of three channel bits. Therefore, when attention is directed tothe logical “1s” of sync patterns occurring after every other logical“1”, the logical “1s” of sync patterns invariably have an interval of“7”.

Thus, a sync pattern can be formed by breaking the regularity of theinterval at which every other logical “1” occurs. A sync pattern“01000010010100” where the intervals at which every other logical “1”occurs are “8, 5, and 6” as shown in FIG. 14A is set as a first syncpattern SA. A sync pattern “01000101001000” where the intervals at whichevery other logical “1” occurs are “6, 5, and 8” as shown in FIG. 14B isset as a second sync pattern SB. Thus, in the second embodiment, a framesync of 14 channel bits is inserted into the disk ID recording format.

FIG. 15 is a block diagram showing a configuration of a disk IDrecording apparatus 11 for recording the disk ID according to the secondembodiment. Parts corresponding to those of the disk ID recordingapparatus 11 described with reference to FIG. 8 are identified by thesame reference numerals, and their description will be omitted whereappropriate (the same will apply hereinafter). Specifically, the disk IDrecording apparatus 11 of FIG. 15 has the same configuration as that ofthe disk ID recording apparatus 11 of FIG. 8 except that the disk IDrecording apparatus 11 of FIG. 15 is provided with a 4-1 modulation unit111 in place of the PE modulation unit 22 in FIG. 8. Therefore,operation of the disk ID recording apparatus 11 of FIG. 15 is the sameas that of the disk ID recording apparatus 11 of FIG. 8 except themodulation method.

When the disk ID recording apparatus 11 of FIG. 15 records the disk IDrecording format as described with reference to FIG. 12 on the circle ofthe BCA 26A of an optical disk 26, a PLL may be operated such that onerotation of the optical disk 26 is in synchronism with n×m×k of FIG. 12.For example, when the wave number of an FG signal outputted from aspindle motor 27 is 42 and then a frequency dividing coefficient N of afrequency divider 30 is set at 58, the cycle of a channel clockoutputted from a VCO 33 becomes equal to 1/(3×2×406) of one rotation ofthe optical disk 26.

The configuration of a disk recording and playback apparatus 51 forrecording data and reproducing data recorded in a data area 26B of theoptical disk 26 having the disk ID information recorded by the disk IDrecording apparatus 11 by the 4-1 modulation method is basically thesame as shown in FIG. 9. However, processing of a demodulation unit 68of the disk recording and playback apparatus 51 is different from thatof the demodulation unit 68 shown in FIG. 9.

Channel position correction made by the demodulation unit 68 will bedescribed with reference to FIGS. 16A through 16G. Also in this case, asin the first embodiment, description will be made assuming that p=3.

A reproduced pit waveform (FIG. 16A) outputted from an LPF 66 isbinarized by a comparator 67, and then inputted to the demodulation unit68 as a binarized pit signal (FIG. 16B). The demodulation unit 68 delaysthe binarized pit signal inputted thereto by a certain time andgenerates a pit center signal (FIG. 16D) that rises precisely at acenter of a period in which the binarized pit signal is a logical “1”.The demodulation unit 68 includes a window generator for generating awindow for counters 1 to 3 and sync pattern detection (that is, a windowfor reading a binarized signal of a reproduced pit when the value of thecounter 2 is “0” to “2”) (FIG. 16C). The counter 1 (FIG. 16E) counts thenumber of clocks (0 to p−1) within a channel bit. The counter 2 (FIG.16F) counts the seven channel bits of the 4-1 modulation. The counter 3(FIG. 16G) counts the number of words of the 4-1 modulation.

The channel position correction is made so that the value of the counter1 becomes “1” when a pit center (FIG. 16D) is detected. For example, thevalue of the counter 1 is corrected to be “1” in timing C in FIG. 16D inwhich a pit center is detected. In addition, word position correction ismade so that a pit center (FIG. 16D) of a sync pattern is located at thecenter of a window (FIG. 16C). For example, the values of the counter 1and the counter 2 are corrected to be “1” in timing D.

A plurality of frame syncs are arranged at equal intervals for onerotation of the optical disk 26. Therefore, even when a frame sync of aframe is not detected, it is possible to reproduce data succeeding theframe sync without loss of the data on the basis of interpolating timingof a frame sync previously detected.

As shown in FIG. 17, when a frame sync (“01000010010100” or“01000101001000”) described with reference to FIGS. 14A and 14B isdetected, the values of the counters 1 to 3 are initialized to “0”.

Description will next be made of a case, as a third embodiment, in whichthe ECC format of disk ID information recorded in the register 21 isencoded by an RS (32, 16, 17) code of GF (2⁸) as shown in FIG. 18,16-byte parity is added to form one block, and the same block issubjected to 4-1 modulation and then written triply around the disk.

In this case, as shown in FIGS. 19A and 19B, a sync pattern of a framesync is formed by adding one word as sync ID to each of the syncpatterns SA and SB described with reference to FIGS. 14A and 14B. A syncpattern of a frame sync thus has a total of 21 channel bits. Hence, thesync ID makes it possible to represent four kinds of sync patterns byusing each of the sync patterns SA and SB and thus form a total of eightsync patterns.

Accordingly, as shown in FIG. 20, it is possible to divide one blockinto eight frames.

In this case, n=3 and m=8. Data of 32 bits is disposed in one frame. Thedata is converted into 112 channel bits by 4-1 modulation, and thereforethe value of k is 133 channel bits (=21+112).

The optical disk 26 is for example a CD (Compact Disk), an MD(Mini-Disk), a DVD (Digital Versatile Disk) or the like.

The series of processing steps described above may also be carried outby software. The software is installed from a recording medium onto acomputer where programs forming the software are incorporated indedicated hardware, or a general-purpose personal computer, for example,which can perform various functions by installing various programsthereon.

Examples of the recording medium include program-recorded package mediadistributed to users to provide a program separately from computers,such as the magnetic disks 41 and 91 (including floppy disks), theoptical disks 42 and 92 (including CD-ROM (Compact Disk-Read OnlyMemory) and DVD (Digital Versatile Disk)), the magneto-optical disks 43and 93 (including MD (Mini-Disk)), or the semiconductor memories 44 and94, as shown in FIG. 8, FIG. 9, or FIG. 15.

As described above, the disk-like recording medium according to thepresent invention comprises: n blocks arranged by dividing a circle of asecond area into n equal parts; and m frames arranged by dividing eachof the blocks into m equal parts; wherein auxiliary information isarranged in the frames in such a manner as to be at equal intervals in acircumferential direction, and a synchronization signal is disposed ineach of the frames. Therefore, it is possible to realize a disk allowingthe auxiliary information to be read easily and reliably without using aPLL.

The disk recording apparatus and the disk recording method according tothe present invention form n blocks by dividing a second area of a diskinto n equal parts in a circumferential direction, form m frames bydividing each of the blocks into m equal parts in the circumferentialdirection, generate channel clocks by dividing each of the frames into kequal parts, control rotation of the disk so that one rotation of thedisk is in synchronism with a cycle of n×m×k channel clocks, modulateauxiliary information on the basis of the channel clocks, and thenrecord the auxiliary information on the disk. Therefore, it is possibleto realize a disk allowing the auxiliary information to be reproducedeasily and reliably without using a PLL.

The disk playback apparatus and the disk playback method according tothe present invention sample a reproduced signal from a disk by a clockhaving a frequency twice n×m×k or higher, and demodulate channel bits,or words while correcting the channel bits, or the words. Therefore, itis possible to reproduce auxiliary information easily and reliablywithout using a PLL.

In each of the above cases, when a plurality of blocks are provided andauxiliary information is written multiply, it is possible toequivalently form a product code and thus realize a high correctioncapability.

Since the circle of the disk is in a substantially physically uniformstate, it is possible to reduce effects on a focus servo and the likeand to control deterioration of the disk.

Even if a defect is caused on the disk, it is possible to correctchannel bits, or words. It is therefore possible to achieve highreliability in reproducing auxiliary information. Also, the redundancyof a synchronization signal may be at a low level.

The present invention is not limited to the details of the abovedescribed preferred embodiments. The scope of the invention is definedby the appended claims and all changes and modifications as fall withinthe equivalence of the scope of the claims are therefore to be embracedby the invention.

1. A recording medium for recording information comprising: a first areafor recording contents data of said disk by a predetermined code; asecond area other than the first area, said second area having framesincluding a frame sync byte and data bytes; wherein said data bytesinclude a sync part and a data part, and wherein said data bytes aremodulated from two data bits to generate a sync pattern of three channelbits followed by four data channel bits for the data part.
 2. Arecording medium according to claim 1, wherein said sync pattern ofthree channel bits has just one logical 1 at a constant position andsaid four data channel bits have just one logical 1 at a positionaccording to said data bytes.
 3. A recording medium as claimed in claim1, further comprising: an error correction code included in said databytes to be used to determine correct information.
 4. A recording mediumas claimed in claim 3, wherein the error correction is obtained bycollecting portions determined by majority rule.
 5. A recording mediumas claimed in claim 1, wherein a first frame of the second area includesa preamble in which the data bytes are all zeroes.
 6. A recording mediumas claimed in claim 1, wherein the second area is an innermostcircumference of the recording medium.
 7. A recording apparatus forrecording data onto a recording medium having a first area for recordingcontents data and a second area other than the first area, saidapparatus comprising: a recording unit operable to record informationonto said recording medium, wherein the information is recorded into thefirst area for recording contents data of said disk by a predeterminedcode; said second area having frames including a frame sync byte anddata bytes; wherein said data bytes include a sync part and a data part,and wherein said data bytes are modulated from two data bits to generatea sync pattern of three channel bits followed by four data channel bitsfor the data part.
 8. A recording apparatus according to claim 7,wherein said sync pattern of three channel bits has just one logical 1at a constant position and said four data channel bits have just onelogical 1 at a position according to said data bytes.
 9. A recordingapparatus as claimed in claim 7, wherein an error correction code isincluded in said data bytes to be used to determine correct information.10. A recording apparatus as claimed in claim 7, wherein the errorcorrection is obtained by collecting portions determined by majorityrule.
 11. A recording apparatus as claimed in claim 7, wherein a firstframe of the second area includes a preamble in which the data bytes areall zeroes.
 12. A recording apparatus as claimed in claim 7, wherein thesecond area is an innermost circumference of the recording medium.
 13. Amethod for recording data onto a recording medium having a first areafor recording contents data and a second area other than the first area,said method comprising: rotating said recording medium; recording saidinformation onto said recording medium; wherein the information isrecorded into the first area for recording contents data of said disk bya predetermined code; said second area having frames including a framesync byte and data bytes; wherein said data bytes include a sync partand a data part, and wherein said data bytes are modulated from two databits to generate a sync pattern of three channel bits followed by fourdata channel bits for the data part.
 14. A recording method according toclaim 13, wherein said sync pattern of three channel bits has just onelogical 1 at a constant position and said four data channel bits havejust one logical 1 at a position according to said data bytes.
 15. Arecording method as claimed in claim 13, further comprising: an errorcorrection code included in said data bytes to be used to determinecorrect auxiliary information.
 16. A recording method as claimed inclaim 13, wherein the error correction is obtained by collectingportions determined by majority rule.
 17. A recording method as claimedin claim 13, wherein a first frame of the second area includes apreamble in which the data bytes are all zeroes.
 18. A recording methodas claimed in claim 13, wherein the second area is an innermostcircumference of the recording medium.
 19. A reproduction apparatus forreproducing data from a recording medium having a first area for storingcontents data and a second area other than the first area, saidapparatus comprising: a driver operable to rotate said recording medium;a reproduction unit operable to reproduce information from saidrecording medium; wherein the information is recorded into the firstarea for recording contents data of said disk by a predetermined code;said second area having frames including a frame sync byte and databytes; wherein said data bytes include a sync part and a data part, andwherein said data bytes are modulated from two data bits to generate async pattern of three channel bits followed by four data channel bitsfor the data part.
 20. A reproduction apparatus according to claim 19,wherein said sync pattern of three channel bits has just one logical 1at a constant position and said four data channel bits have just onelogical 1 at a position according to said data bytes.
 21. A reproductionapparatus as claimed in claim 19, wherein an error correction code isincluded in said data bytes to be used to determine correct information.22. A reproduction apparatus as claimed in claim 19, wherein the errorcorrection is obtained by collecting portions determined by majorityrule.
 23. A reproduction apparatus as claimed in claim 19, wherein afirst frame of the second area includes a preamble in which the databytes are all zeroes.
 24. A reproduction apparatus as claimed in claim19, wherein the second area is an innermost circumference of therecording medium.
 25. A method for reproducing data from a recordingmedium having a first area for storing user data and a second area otherthan the first area, said method comprising: rotating said recordingmedium; reproducing information from said recording medium; wherein theinformation is recorded into the first area for recording contents dataof said disk by a predetermined code; said second area having framesincluding a frame sync byte and data bytes; wherein said data bytesinclude a sync part and a data part, and wherein said data bytes aremodulated from two data bits to generate a sync pattern of three channelbits followed by four data channel bits for the data part.
 26. Areproducing method according to claim 25, wherein said sync pattern ofthree channel bits has just one logical 1 at a constant position andsaid four data channel bits have just one logical 1 at a positionaccording to said data bytes.
 27. A reproducing method as claimed inclaim 25, wherein an error correction code is included in said databytes to be used to determine correct information.
 28. A reproducingmethod as claimed in claim 25, wherein the error correction is obtainedby collecting portions determined by majority rule.
 29. A reproducingmethod as claimed in claim 25, wherein a first frame of the second areaincludes a preamble in which the data bytes are all zeroes.
 30. Areproducing method as claimed in claim 25, wherein the second area is aninnermost circumference of the recording medium.